


Size Matters

by fermentedpixiecum



Category: Undertale (Video Game), underswap
Genre: F/M, Reader Is Not Frisk, Reader has a vagina, Sex, Vaginal Penetration, baby's first smut???, ectodick, girth growth, please, please be kind on me, this is my first writing
Language: English
Status: Completed
Published: 2017-03-08
Updated: 2017-03-08
Packaged: 2018-09-30 20:11:09
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,032
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10170911
Author URL: https://archiveofourown.org/users/fermentedpixiecum/pseuds/fermentedpixiecum
Summary: Papyrus is more than happy to apply to your needs.such a shitty summary but, enjoyy~!





	

Sex with Papyrus was always something that excited you, especially with the way he gripped onto your hips like it was the only thing keeping him from falling into complete bliss. The way he kept you close made you feel a certain type of specialty. Of course, there was something that bothered you. Well, it never bothered you it was more of something that made you wonder. Papyrus was able to manifest himself something to satisfy you when you two got heated, and while it was always absolutely amazing there was always a question that lingered in the back of your mind.

 

" Mhn..Pap.." You tried to capture his attention, though it only spurred him to answer back with his own groan of pleasure.

 

Swallowing down your thoughts, you pushed yourself from holding onto his shoulders and looked up towards him, your cheeks flushed with embarrassment." Papyrus.." You tried once more, thankfully being more successful this time around. His slow movements stopped, his bone-brows furrowing with confusion and worry." You doin' alright, sugar?" His worry made your heart swell, his caring nature always got to you." I-I'm fine, I just..." You paused, embarrassment suddenly flooding you as you thought about the question you were just about to ask. How would one even bring this up? Your worst fear was it offending him, hell even worse make him upset with you. You didn't want him to feel like he wasn't doing a good job, because god he was.

 

You just wanted something  _ bigger _ .

 

Was that too much to ask for? You let out a frustrated sigh, which only worried Papyrus even more. Gently placing his hand on your cheek, he brought your face up to look at him." Talk to me, babygirl. I ain't doin' anything wrong am I? " He wondered aloud, you were quick to deny it." God no! You're doing wonderfully, like you always do. I, uhm, I just wanted to ask something. " Embarrassment began to crawl up your spine once more, him nodding for you to carry on only made you want to hide your face in shame. Was it really wrong to ask this? Taking a deep breathe, you swallowed down your fears and spoke." Well, I was wondering if you can... make yourself bigger?"

 

The room broke out in silence, which only fed the anxiety building in the pit of your stomach. Your mind was running wild with regret and shame, it felt like time had stopped and you had just made the worst mistake of your entire life. You didn't know what to do, the silence was killing you. Had you upset him? Did he want to stop and leave? You thought about laughing it off and playing it as a joke but before you could do anything your thoughts were cut short by a deep chuckle that came from your skeletal boyfriend.

 

" Oh? You wanna know if I can go bigger? " Papyrus' smirk was more apparent now, causing a shy smile to come to your lips as you nodded at his question. He didn't seem to be angry, which was a good sign so-

 

Oh.  _ Ohhh. _

 

To say you were surprised would be under-exaggerating, you definitely weren't expecting him to comply so quickly. Though what you weren't expecting the most was how immense he made himself. Throwing your head back, you let out a surprised moan at the stretching of your walls. The feeling of his cool, slick tongue against your neck sent you into a trembling mess." Did that ful _ fill _ your expectations? " His husky voice whispered into your ear, only for you to moan back. There was definitely a bulge in your lower abdomen, the feeling only made you shudder more. Chuckling deeply, Papyrus gripped your hips once more and pulled them up, you hands on his shoulders clinging onto him for dear life. As quickly as he has pulled them up, he slammed your hips back down on his shaft, meeting halfway with his own thrust making you scream out.

 

His thrusts were quick and rough, you were sure you'd have bruises on your hips the next morning." Papyruuussss! " You dragged out his name, tongue hanging out and eyes rolled back. Though it seemed like you were trying to move your hips against him to you, he ended up doing all the work as your body limped and clung against him. His own grunts and groans only spurred you on, walls tightening around him as you tried to familiarize yourself with his new girth." _____ ....hnn fuck! " 

 

The room was filled with the sound of bone against skin, your moans getting higher with each thrust into your body. Why didn’t you ask sooner? Things would have gone so much smoother if you hadn’t been nervous and you would have been able to feel this type of pleasure sooner! You hadn’t noticed that his hands were sliding down your body until you felt his phalanges at the top of your sex, a confused hum escaping you. Your hum turned into a shriek of pleasure, his phalange beginning to circle your pulsing bud.

 

” P-Papy! Oh  _ god _ \- Papyrus! I’m gonna!”

 

His thrusting became erratic, his groans turning to his low growls as he shank his teeth into your shoulder, making you shudder and moan.” Go on babygirl, cum on my cock. Show me how much you love my big cock thrusting into your pussy like this.” And with that, a wave of pure bliss rippled through your body, your walls tightening around him as you let out a choked moan.

 

“ Oh  _ fuck _ ! ____! “ He hadn’t expected you to tighten so much around him, the feeling causing his eyes to roll into the back of his skull as he fell into his own pool of pleasure, his seed spilling into you and spilling out down your thigh.

 

You had gone limp against him, your throat raw and your hips stung. Yeah, you were definitely going to have bruises. You let a small sigh as you felt his hand rubbing your back, a smile coming to your lips at the feeling.

 

“ So glad I was able to  _ fill _ your desires babe.” 

 

“ Papyrus.”

 

“ You must have felt  _ stuffed _ . “

  
“ Papyrus!”

**Author's Note:**

> This is my very first smut writing, please be kind on me. I've always loved US!Papyrus so I was like, why not write some good ol' smut for it? ;0 I hope you guys enjoyed! I based this story off of a comic I saw on tumblr! I can't remember where to find it! Please feel free to leave comments and kudos!


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